The present invention relates to an elastic suspension for front and rear axles of industrial vehicles, particularly vehicles for earth-moving and for similar uses, such as excavators, lift trucks, tractors and the like.
Industrial vehicles with a maximum speed set to approximately 40 km/h conventionally rely on their tires to cushion impacts and vibrations during normal road travel and during use.
This is due to the fact that since at least one axle of these vehicles is not pivoting but is directly coupled to the chassis in a rigid manner, it directly transmits the loads that act on the chassis of the vehicle to the wheels through the axle (which are of the non-independent type); therefore, at the maximum allowed speeds the vehicles tend to bounce, negatively affecting driving safety.
It is also known that for example agricultural tractors have been recently equipped with electronically-controlled hydropneumatic suspensions for their front axles, indeed in order to stabilize the vehicle at the maximum allowed speed; likewise, again in the case of agricultural tractors and the like, it is substantially impossible to use conventional elastic suspensions, such as those constituted by leaf springs, which are arranged longitudinally with respect to the vehicle and connect the front axle to the chassis, owing to the limited front bulk of the agricultural tractor, which does not allow the leaf springs to protrude in front of the chassis, where there is often provided a fork, a loader or the like.
A system is also known which allows to provide a flexible suspension for axles of industrial vehicles, particularly of agricultural tractors, back hoe loaders and the like.
This elastic suspension is preset so that it can be applied to the steered axle of an all-terrain vehicle, for example an agricultural tractor; it is constituted by two axle portions or shanks which are coaxial to the axis of the front axle and to the axis of a torque shaft which is parallel to a first portion of the steering axle; said shanks are arranged at right angles to the axle and in front thereof (in the travel direction) and are mutually rigidly connected by a support or linkage which is parallel to the axle and acts by torque by s of a bridge-like cross-member connected to said torque shaft; to the rear of the bridge there is provided a second support which is parallel to the rear one and oscillates around the cardan shaft. One end of said oscillating support is connected to said portion of the steered axle, whilst the other end is rotatably connected to the end of the torque shaft. Said torque shaft is furthermore connected, through its free end, to the chassis of the vehicle. The axes of the steering shaft, of the cardan shaft and of the torque shaft are arranged on the same plane that contains the steered shaft.
This elastic suspension is structurally rather complicated and bulky, can be used only for the front axle of a tractor, and has no torque adjustment device or element.